The present invention relates to a needle intended for interlacing yarns, strands or flexible cords into an already known structure composed of a shank which is bent at its end to form a blade, defining an eye.
The needle of this type finds application particularly in the manufacture of reinforced multi-directional woven or knitted structures of revolution. Such reinforced structures are used after impregnation with an appropriate binding agent, to make structural assemblies of composite material which may undergo very severe mechanical and thermal stress, for example nozzles, radioelectric antenna, windows for space shuttles, turbine vanes, nose cones of re-entry bodies, armour-plating, etc.
Numerous process for weaving structures of revolution exist, and particularly processes for three-dimensional weaving, in which the circumferential and longitudinal yarns are connected by radial yarns. The needles usually used for making this connection are so-called sewing and/or knitting needles. The former, such as used in French Patent Application No. 76 02943 of Feb. 3, 1976, comprise a closed eye. They carry a stitching yarn knotted with a second yarn past, via a shuttle, in a loop of the first yarn. The latter are latch needles such as described in French Pat. No. 75 20117 of June 26, 1975 and in U.S. Pat. No. 4,149,477.
A latch needle engages, with the latch open, in the structure being woven, hooks a yarn and returns it through the structure, latch closed, the connection between yarns being made by a chain stitch.
In the case of making reinforcements of any form on a woven structure mode on metal rods, the conventional latch needle as used in the above-mentioned patents comprises a head which is too large to be able to perform its function. Due to its constitution, the risks of untimely hooking of the yarns of the woven structure are multiplied not only in case of false maneuver, but also during normal use. Such a risk is run, for example, when the needle enters in the woven fabric, then moves back before its head has emerged on the opposite side. Furthermore, it is sometimes difficult to grip a large number of yarns or a yarn and/or a large strand of yarns with a latch needle, due to its size, insofar as the gripped yarns tend to escape before the latch closes again. If a large number of yarns is to be gripped, it is necessary to use a latch needle having a large-size point, but this leads to a certain fragility in this zone. On the other hand, in woven reinforcements adapted to withstand considerable mechanical and thermal stress, the textile structure most frequently used is a carbon filament or strand, which is very fragile and therefore easily damaged by the mobile latch.